Method of solubilizing itraconazole

ABSTRACT

Solutions comprising itraconazole solubilized in a solvent comprising at least one volatile organic acid are provided. Methods for preparing microspheres containing imidazole derivatives are provided. Also provided is the use of imidazole derivatives containing microspheres for treating fungal infections. Oral dosage forms for oral administration are also provided.

This is a division of application U.S. Ser. No. 08/475,887, filed Jun.7, 1995, now, U.S. Pat. No. 5,750,147.

FIELD OF THE INVENTION

The present invention relates to the preparation of solutions containingimidazole derivatives and to the use of those solutions in thepreparation of microspheres. The imidazole derivative containingmicrospheres are effective in treating fungal infections, particularlyin mammals. The microspheres facilitate the oral administration ofrelatively large amounts of the imidazole derivative, with increasedbioavailability.

BACKGROUND OF THE INVENTION

Many present systems for delivering active agents to targets areseverely limited by biological, chemical, and physical barriers, whichare imposed by the environment through which delivery occurs, theenvironment of the target itself, or the target itself. Delivery is alsolimited, in many instances, by the chemical nature of the active agent.For example, oral delivery is generally ineffective with active agentsthat are poorly water-soluble.

The imidazole derivative family of compounds is particularly effectiveagainst a broad range of fungal infections such as those caused byTrichophyton rubrum, Tricophyton mentagrophytes, Epidermophytonfloccsum, and Candida albicans, but these compounds are either partiallywater soluble or insoluble in water. For example, the solubility ofitraconazole in water is less than 0.00001 g/ml.

Partially because imidazole derivatives are typically insoluble inwater, they are difficult to administer orally. Consequently althoughimidazole derivatives are frequently prescribed for the treatment offungal infections, they have been available only in topical preparationsor in oral formulations with limited bioavailability.

In recent years, fungal infections, such as those caused by Candidaalbicans in particular have become more prevalent and intractable due totheir appearance in immunocompromised patients, such as those infectedwith Human Immunodeficiency Virus (HIV) or those suffering from AcquiredImmunodeficiency Syndrome (AIDS).

For example, U.S. Pat. No. 3,717,655 discloses imidazole derivativeswhich have antifungal and antibacterial activity. These compounds arealmost insoluble in aqueous solutions such as water and are very poorlysoluble in polar solvents such as ethanol.

Das et al., U.S. Pat. No. 4,912,124, disclose a solvent system forimidazole derivatives that include mixtures of a polar solvent, apolyhydric alcohol that acts as a solubilizing agent, a nonionic oramphoteric surfactant, and a cosmetic humectant. Solutions containing atleast 1 percent by weight of the imidazole derivatives can be formulatedusing this solvent system. However, these formulations are suitable forexternal topical use only.

Accordingly, there is a need for orally deliverable forms of imidazolederivative antifungal agents.

SUMMARY OF THE INVENTION

The present invention provides solutions comprising:

(a) at least about 2.5 parts by weight, based upon 100 parts by weightof solution, of a solute having the formula

wherein R, R¹, and R² are independently hydrogen or lower alkyl;

R³ is hydrogen, methyl or ethyl;

R⁴ is hydrogen or methyl

Ar is phenyl, monohalophenyl, dihalophenyl, trihalophenyl, mono(loweralkyl)phenyl, di(lower alkyl)phenyl, lower alkoxyphenyl, or halothienyl;

Ar¹ is phenyl, monohalophenyl, dihalophenyl, trihalophenyl, mono(loweralkyl)phenyl, di(lower alkyl)phenyl, lower alkoxyphenyl, or cyanophenyl;and

n is 1 or 2; and

(b) a solubilizing effective amount of a solvent comprising at least onevolatile organic acid solvent.

Imidazole derivative microspheres are also provided. These microspherescomprise:

(a) an imidazole derivative active agent having the formula ##STR1##wherein R, R¹, and R² are independently hydrogen or lower alkyl;

R³ is hydrogen, methyl or ethyl;

R⁴ is hydrogen or methyl

Ar is phenyl, monohalophenyl, dihalophenyl, trihalophenyl, mono(loweralkyl)phenyl, di(lower alkyl)phenyl, lower alkoxyphenyl, or halothienyl;

Ar¹ is phenyl, monohalophenyl, dihalophenyl, trihalophenyl, mono(loweralkyl)phenyl, di(lower alkyl)phenyl, lower alkoxyphenyl, or cyanophenyl;and

n is 1 or 2; and

(b) a microsphere forming carrier selected from the group consisting of

(i) a proteinoid;

(ii) an acylated amino acid, poly amino acid, or a salt thereof;

(iii) an sulfonated amino acid, poly amino acid, or a salt thereof;

(iv) a protein or a salt thereof;

(v) an enteric coating material; or

(vi) any combination thereof.

Also contemplated by the present invention is a method for preparingthese microspheres. The method comprises:

(A) nebulizing a solution comprising

(a) an imidazole active agent having the formula ##STR2## wherein R, R¹,and R² are independently hydrogen or lower alkyl;

R³ is hydrogen, methyl or ethyl;

R⁴ is hydrogen or methyl

Ar is phenyl, monohalophenyl, dihalophenyl, trihalophenyl, mono(loweralkyl)phenyl, di(lower alkyl)phenyl, lower alkoxyphenyl, or halothienyl;

Ar¹ is phenyl, monohalophenyl, dihalophenyl, trihalophenyl, mono(loweralkyl)phenyl, di(lower alkyl)phenyl, lower alkoxyphenyl, or cyanophenyl;and

n is 1 or 2;

(b) an active agent and carrier solubilizing effective amount of asolvent comprising an aqueous solution of at least one volatile organicsolvent; and wherein the volume:volume ratio of acid to water in saidcarrier solution is at least about 3:7, and

(c) microsphere forming a carrier selected from the group consisting of

(i) a proteinoid;

(ii) an acylated amino acid or poly amino acid or a salt thereof;

(iii) an sulfonated amino acid or poly amino acid or a salt thereof;

(iv) a protein or a salt thereof;

(v) an enteric coating material; or

(vi) any combination thereof; and

(B) decreasing said ratio to less than about 3:7, to yield saidmicrospheres. Alternatively, the active agent and the carrier can besolubilized in separate solutions. The separate solutions can benebulized together and the acid to water ratio then decreased as above.

Methods for the oral administration of imidazole derivatives are alsocontemplated wherein the microsphere compositions above are orallyadministered to an animal in need of this treatment.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a scanning electron micrograph (SEM) taken at a magnificationof 2,000× of microspheres containing itraconazole prepared according tothe present invention.

FIG. 1B is a SEM taken at a magnification of 15,000× of microspherescontaining itraconazole prepared according to the present invention.

FIG. 1C is a SEM taken a magnification of 20,000× of microspherescontaining itraconazole prepared according to the present invention.

FIG. 1D is a SEM taken at a magnification of 20,000× of microspherescontaining itraconazole prepared according to the present invention.

FIG. 1E is a SEM taken at a magnification of 20,000× of microspherescontaining itraconazole prepared according to the present invention.

FIG. 1F is a SEM taken at a magnification of 20,000× of microspherescontaining itraconazole prepared according to the present invention.

FIG. 1G is a SEM taken at a magnification of 2,000× of microspherescontaining itraconazole prepared according to the present invention,after being mechanically crushed.

FIG. 1H is a SEM taken at a magnification of 3,500× of microspherescontaining itraconazole prepared according to the present invention,after being mechanically crushed.

DETAILED DESCRIPTION OF THE INVENTION

It has now been discovered that water insoluble or partially solubleimidazole derivatives can be solubilized in volatile organic acids. Theresultant solutions can be used to prepare imidazole containingmicrospheres which are suitable for oral administration to animals.

Imidazole Derivatives

The active agents of the present invention are imidazole derivativeshaving the formula: ##STR3## wherein R, R¹ and R² are independentlyhydrogen or lower alkyl; R³ is hydrogen, methyl or ethyl;

R⁴ is hydrogen or methyl

Ar is phenyl, monohalophenyl, dihalophenyl, trihalophenyl, mono (loweralkyl)phenyl, di(lower alkyl)phenyl, lower alkoxyphenyl, or halothienyl;

Ar¹ is phenyl, monohalophenyl, dihalophenyl, trihalophenyl, mono(loweralkyl)phenyl, di(lower alkyl)phenyl, lower alkoxyphenyl, or cyanophenyl;and

n is 1 or 2.

A preferred imidazole derivative is itraconazole. Itraconazole is asynthetic triazole imidazole derivative 1:1:1:1 racemic mixture of fourdiastereomers (two enantiomeric pairs), each possessing three chiralcenters (Physicians Desk Reference 48th Ed., pg. 1097, 1994).

Imidazole Derivative Solutions

The solutions prepared in accordance with the present invention allowfor the solubilization of imidazole derivatives at concentrationssuitable for processing into orally administrable forms havingacceptable bioavailability.

In accordance with the present invention, imidazole derivatives aresolubilized in volatile organic acid solvent(s). Preferred acid solventsfor the imidazole derivatives are acetic acid and formic acid.Preferably, the solvent itself is an aqueous solution of the acid. Mostpreferably the volume:volume ratio of the acid to the total volume ofthe solvent is 3:7 or greater. It has been found that by using thissolvent system up to a 50% solution of imidazole derivative can beprepared.

Dissolution is achieved by simple mixing, with heating if necessary. Themore concentrated the acid in the solvent, the greater the amount ofactive agent that can be incorporated into the solution. If lowerconcentrations of acid are required for the end use of the solution, theactive agent can first be dissolved in a more concentrated acidsolution, and the resultant solution then slowly diluted further,preferably with water.

Preferably, the solution comprises from about 3 to about 40 percent byweight of solute and from about 60 to about 97 parts by weight ofsolvent based upon 100 parts by weight of solution.

The solvent itself, preferably comprises from about 30 to about 80 partsby volume of acid and from about 70 to about 20 parts by volume of waterbased upon 100 parts by volume of solvent. Most preferably, the solventcomprises from about 40 to about 50 parts by volume of acid and fromabout 60 to about 50 parts by volume of water based upon 100 parts byvolume of solvent.

Microspheres

Microspheres are useful in the delivery of active agents because theyprotect an active agent cargo until it is delivered to a target.Microspheres are particularly useful in the oral delivery ofbiologically active agents such as, for example, pharmaceutically activeagents.

Microspheres containing an active agent can be generally of the matrixform or the capsule form. In a hollow matrix spheroid form, the centerof the sphere is hollow and the cargo or active agent is distributedthroughout a carrier matrix. In a solid matrix form, the carrier matrixforms a continuum in which the cargo is distributed. In the microcapsuleform, the encapsulated material or cargo can be either in solution or asolid, with the carrier forming a shell around the cargo.

The methods of the present invention are cost-effective for preparingmicrospheres which contain imidazole derivatives, are simple to perform,and are amenable to industrial scale-up for commercial production.

Carriers

Carriers suitable for use in the present invention are microsphereforming carriers. These carriers include, without limitation,proteinoids; acylated amino acids, poly amino acids or salts thereof;sulfonated amino acids, poly amino acids or salts thereof; proteins orsalts thereof, enteric coating materials; or any combination thereof.

Amino acids are the basic materials used to prepare many of the carriersuseful in the present invention. Amino acids include any carboxylic acidhaving at least one free amino group and include naturally occurring andsynthetic amino acids. The preferred amino acids for use in the presentinvention are '-amino acids and, most preferably, are naturallyoccurring '-amino acids. Many amino acids and amino acid esters arereadily available from a number of commercial sources such as AldrichChemical Co. (Milwaukee, Wis., USA); Sigma Chemical Co. (St. Louis, Mo.,USA); and Fluka Chemical Corp. (Ronkonkoma, N.Y., USA).

Representative, but not limiting, amino acids suitable for use in thepresent invention are generally of the formula ##STR4## wherein: R⁵ ishydrogen, C₁ -C₄ alkyl, or C₂ -C₄ alkenyl;

R⁶ is C₁ -C₂₄ alkyl, C₂ -C₂₄ alkenyl, C₃ -C₁₀ cycloalkyl, C₃ -C₁₀cycloalkenyl, phenyl, naphthyl, (C₁ -C₁₀ alkyl) phenyl, (C₂ -C₁₀alkenyl) phenyl, (C₁ -C₁₀ alkyl) naphthyl, (C₂ -C₁₀ alkenyl) naphthyl,phenyl (C₁ -C₁₀ alkyl), phenyl (C₂ -C₁₀ alkenyl), naphthyl (C₁ -C₁₀alkyl), or naphthyl (C₂ -C₁₀ alkenyl);

R⁶ being optionally substituted with C₁ -C₄ alkyl, C₂ -C₄ alkenyl, C₁-C₄ alkoxy, --OH, --SH, --CO₂ R⁷, C₃ -C₁₀ cycloalkyl, C₃ -C₁₀cycloalkenyl, heterocycle having 3-10 ring atoms wherein the hetero atomis one or more of N, O, S, or any combination thereof, aryl, (C₁ -C₁₀alk)aryl, ar(C₁ -C₁₀ alkyl) or any combination thereof;

R⁶ being optionally interrupted by oxygen, nitrogen, sulfur, or anycombination thereof; and

R⁷ is hydrogen, C₁ -C₄ alkyl, or C₂ -C₄ alkenyl.

The preferred naturally occurring amino acids for use in the presentinvention as amino acids or components of a peptide are alanine,arginine, asparagine, aspartic acid, citrulline cysteine, cystine,glutamic acid, glutamine, glycine, histidine, isoleucine, leucine,lysine, methionine, ornithine, phenylalanine, proline, serine,threonine, tryptophan, tyrosine, valine, hydroxyproline,β-carboxyglutamic acid, γ-carboxyglutamic acid, phenylglycine, orO-phosphoserine. The most preferred amino acids are arginine, leucine,lysine, phenylalanine, tyrosine, tryptophan, valine, and phenylglycine.

The preferred non-naturally occurring amino acids for use in the presentinvention are β-alanine, α-amino butyric acid, γ-amino butyric acid,γ-(aminophenyl) butyric acid, α-amino isobutyric acid, ε-amino caproicacid, 7-amino heptanoic acid, β-aspartic acid, aminobenzoic acid,aminophenyl acetic acid, aminophenyl butyric acid, γ-glutamic acid,cysteine (ACM), ε-lysine, methionine sulfone, norleucine, norvaline,ornithine, d-ornithine, p-nitro-phenylalanine, hydroxy proline,1,2,3,4,-tetrahydroisoquinoline-3-carboxylic acid, and thioproline.

Poly amino acids are either peptides or two or more amino acids linkedby a bond formed by other groups which can be linked, e.g., an ester oran anhydride linkage. Special mention is made of non-naturally occurringpoly amino acids and particularly non-naturally occurring hetero-polyamino acids, i.e. of mixed amino acids.

Peptides are two or more amino acids joined by a peptide bond. Peptidescan vary in length from di-peptides with two amino acids to polypeptideswith several hundred amino acids. See, Walker, Chambers BiologicalDictionary, Cambridge, England: Chambers Cambridge, 1989, page 215.Special mention is made of non-naturally occurring peptides andparticularly non-naturally occurring peptides of mixed amino acids.Special mention is also made of di-peptides tri-peptides,tetra-peptides, and penta-peptides, and particularly, the preferredpeptides are di-peptides and tri-peptides. Peptides can be homo- orhetero-peptides and can include natural amino acids, synthetic aminoacids, or any combination thereof.

Proteinoids

Proteinoids are artificial polymers of amino acids. Proteinoidspreferably are prepared from mixtures of amino acids. Preferredproteinoids are condensation polymers, and most preferably, are thermalcondensation polymers. These polymers may be directed or randompolymers. Proteinoids can be linear, branched, or cyclical, and certainproteinoids can be units of other linear, branched, or cyclicalproteinoids.

Special mention is made of diketopiperazines. Diketopiperazines are sixmember ring compounds. The ring includes two nitrogen atoms and issubstituted at two carbons with two oxygen atoms. Preferably, thecarbonyl groups are at the 2 and 5 ring positions. These rings can beoptionally, and most often are, further substituted.

Diketopiperazine ring systems may be generated during thermalpolymerization or condensation of amino acids or amino acid derivatives.(Gyore, J; Ecet M. Proceedings Fourth ICTA (Thermal Analysis), 1974, 2,387-394 (1974)). These six membered ring systems were presumablygenerated by intra-molecular cyclization of the dimer prior to furtherchain growth or directly from a linear peptide (Reddy, A. V., Int. J.Peptide Protein Res., 40, 472-476 (1992); Mazurov, A. A. et al., Int. J.Peptide Protein Res., 42, 14-19 (1993)).

Diketopiperazines can also be formed by cyclodimerization of amino acidester derivatives as described by Katchalski et al., J. Amer. Chem.Soc., 68, 879-880 (1946), by cyclization of dipeptide ester derivatives,or by thermal dehydration of amino acid derivatives and high boilingsolvents as described by Kopple et al., J. Org. Chem., 33 (2), 862-864(1968).

Diketopiperazines typically are formed from α-amino acids. Preferably,the α-amino acids of which the diketopiperazines are derived areglutamic acid, aspartic acid, tyrosine, phenylalanine, and opticalisomers of any of the foregoing.

Modified Amino Acids and Poly Amino Acids

Modified amino acids, poly amino acids, or peptides are either acylatedor sulfonated and include amino acid amides and sulfonamides.

Acylated Amino Acids and Poly Amino Acids

Although any acylated amino acids or poly amino acids are useful in thepresent invention, special mention is made of acylated amino acidshaving the formula

    Ar.sup.2 --Y--(R.sup.8).sub.n --OH                         III

wherein Ar² is a substituted or unsubstituted phenyl or naphthyl;##STR5## R⁸ has the formula ##STR6## wherein: R⁹ is C₁ to C₂₄ alkyl, C₁to C₂₄ alkenyl, phenyl, naphthyl, (C₁ to C₁₀ alkyl) phenyl, (C₁ to C₁₀alkenyl) phenyl, (C₁ to C₁₀ alkyl) naphthyl, (C₁ to C₁₀ alkenyl)naphthyl, phenyl (C₁ to C₁₀ alkyl), phenyl (C₁ to C₁₀ alkenyl), naphthyl(C₁ to C₁₀ alkyl) and naphthyl (C₁ to C₁₀ alkenyl);

R⁹ is optionally substituted with C₁ to C₄ alkyl, C₁ to C₄ alkenyl, C₁to C₄ alkoxy, --OH, --SH and --CO₂ R¹¹, cycloalkyl, cycloalkenyl,heterocyclic alkyl, alkaryl, heteroaryl, heteroalkaryl, or anycombination thereof;

R¹¹ is hydrogen, C₁ to C₄ alkyl or C₁ to C₄ alkenyl;

R⁹ is optionally interrupted by oxygen, nitrogen, sulfur or anycombination thereof; and

R¹⁰ is hydrogen, C₁ to C₄ alkyl or C₁ to C₄ alkenyl.

Special mention is also made of those having the formula ##STR7##wherein: R¹² is (i) C₃ -C₁₀ cycloalkyl, optionally substituted with C₁-C₇ alkyl, C₂ -C₇ alkenyl, C₁ -C₇ alkoxy, hydroxy, phenyl, phenoxy or--CO₂ R¹⁵, wherein R¹⁵ is hydrogen, C₁ -C₄ alkyl, or C₂ -C₄ alkenyl; or

(ii) C₁ -C₆ alkyl substituted with C₃ -C₁₀ cycloalkyl;

R¹³ is hydrogen, C₁ -C₄ alkyl, or C₂ -C₄ alkenyl;

R¹⁴ is C₁ -C₂₄ alkyl, C₂ -C₂₄ alkenyl, C₃ -C₁₀ cycloalkyl, C₃ -C₁₀cycloalkenyl, phenyl, naphthyl, (C₁ -C₁₀ alkyl) phenyl, (C₂ -C₁₀alkenyl) phenyl, (C₁ -C₁₀ alkyl) naphthyl, (C₂ -C₁₀ alkenyl) naphthyl,phenyl (C_(l) -C₁₀ alkyl), phenyl (C₂ -C₁₀ alkenyl), naphthyl (C₁ -C₁₀alkyl) or naphthyl (C₂ -C₁₀ alkenyl);

R¹⁴ being optionally substituted with C₁ -C₄ alkyl, C₂ -C₄ alkenyl, C₁-C₄ alkoxy, --OH, --SH, --CO₂ R¹⁶, C₃ -C₁₀ cycloalkyl, C₃ -C₁₀cycloalkenyl, heterocycle having 3-10 ring atoms wherein the hetero atomis one or more of N, O, S or any combination thereof, aryl, (C₁ -C₁₀alk)aryl, ar(C₁ -C₁₀ alkyl), or any combination thereof;

R¹⁴ being optionally interrupted by oxygen, nitrogen, sulfur, or anycombination thereof; and

R¹⁶ is hydrogen, C₁ -C₄ alkyl, or C₂ -C₄ alkenyl.

Acylated amino acids may be prepared by reacting single amino acids,mixtures of two or more amino acids, or amino acid esters with an aminemodifying agent which reacts with free amino moieties present in theamino acids to form amides.

Suitable, but non-limiting, examples of acylating agents useful inpreparing acylated amino acids include

acid chloride acylating agents having the formula ##STR8## wherein: R¹⁷an appropriate group for the modified amino acid being prepared, suchas, but not limited to, alkyl, alkenyl, cycloalkyl, or aromatic, andparticularly methyl, ethyl, cyclohexyl, cyclophenyl, phenyl, or benzyl,and X is a leaving group. Typical leaving groups include, but are notlimited to, halogens such as chlorine, bromine and iodine.

Examples of the acylating agents include, but are not limited to, acylhalides including, but not limited to, acetyl chloride, propyl chloride,cyclohexanoyl chloride, cyclopentanoyl chloride, and cycloheptanoylchloride, benzoyl chloride, hippuryl chloride and the like; andanhydrides, such as acetic anhydride, propyl anhydride, cyclohexanoicanhydride, benzoic anhydride, hippuric anhydride and the like. Preferredacylating agents include benzoyl chloride, hippuryl chloride, acetylchloride, cyclohexanoyl chloride, cyclopentanoyl chloride, andcycloheptanoyl chloride.

The amine groups can also be modified by the reaction of a carboxylicacid with coupling agents such as the carbodiimide derivatives of aminoacids, particularly hydrophilic amino acids such as phenylalanine,tryptophan, and tyrosine. Further examples includedicyclohexylcarbodiimide and the like.

If the amino acid is multifunctional, i.e. has more than one --OH, --NH₂or --SH group, then it may optionally be acylated at one or morefunctional groups to form, for example, an ester, amide, or thioesterlinkage.

In acylated poly amino acids, one or more of the amino acids may bemodified (acylated). Modified poly amino acids may include one or moreacylated amino acid(s). Although linear modified poly amino acids willgenerally include only one acylated amino acid, other poly amino acidconfigurations can include more than one acylated amino acid. Poly aminoacids can be polymerized with the acylated amino acid(s) or can beacylated after polymerization.

Sulfonated Amino Acids and Poly Amino Acids

Sulfonated amino acids and poly amino acids are modified by sulfonatingat least one free amine group with a sulfonating agent which reacts withat least one of the free amine groups present.

Special mention is made of compounds of the formula

    Ar.sup.3 --Y--(R.sup.18).sub.n --OH                        V

wherein Ar³ is a substituted or unsubstituted phenyl or naphthyl;

Y is --SO₂ --, R¹⁸ has the formula ##STR9## wherein: R¹⁹ is C₁ to C₂₄alkyl, C₁ to C₂₄ alkenyl, phenyl, naphthyl, (C₁ to C₁₀ alkyl) phenyl,(C₁ to C₁₀ alkenyl) phenyl, (C₁ to C₁₀ alkyl) naphthyl, (C₁ to C₁₀alkenyl) naphthyl, phenyl (C₁ to C₁₀ alkyl), phenyl (C₁ to C₁₀ alkenyl),naphthyl (C₁ to C₁₀ alkyl) and naphthyl (C₁ to C₁₀ alkenyl);

R¹⁹ is optionally substituted with C₁ to C₄ alkyl, C₁ to C₄ alkenyl, C₁to C₄ alkoxy, --OH, --SH and --CO₂ R²¹ or any combination thereof;

R²¹ is hydrogen, C₁ to C₄ alkyl or C₁ to C₄ alkenyl;

R¹⁹ is optionally interrupted by oxygen, nitrogen, sulfur or anycombination thereof; and

R²⁰ is hydrogen, C₁ to C₄ alkyl or C₁ to C₄ alkenyl.

Suitable, but non-limiting, examples of sulfonating agents useful inpreparing sulfonated amino acids include sulfonating agents having theformula R²² --SO₂ --X wherein R²² is an appropriate group for themodified amino acid being prepared such as, but not limited to, alkyl,alkenyl, cycloalkyl, or aromatics and X is a leaving group as describedabove. One example of a sulfonating agent is benzene sulfonyl chloride.

Modified poly amino acids and peptides may include one or moresulfonated amino acid(s). Although linear modified poly amino acids andpeptides used generally include only one sulfonated amino acid, otherpoly amino acid and peptide configurations can include more than onesulfonated amino acid. Poly amino acids and peptides can be polymerizedwith the sulfonated amino acid(s) or can be sulfonated afterpolymerization.

Proteins

Proteins are naturally occurring (i.e. not artificial) polymers of aminoacids.

Enteric Coating Materials

Enteric coating materials known to those skilled in the art such as, forexample, cellulose acetate trimellitate (CAT) and cellulose acetatephthalate (CAP), are suitable for use in the preservation as well.

Formation

These carriers, and particularly proteinoids, acylated amino acids orpoly amino acids, sulfonated amino acids or poly amino acids, andproteins are often insoluble or relatively insoluble in neutral ormildly acidic solutions but are also soluble, as are the imidazolederivatives useful in the present invention, in aqueous acid solutionswherein the volume to volume ratio of acid to water is greater thanabout 3:7. Suitable aqueous acid solvents are as above, i.e. volatileorganic acids, such as for example, aqueous acetic acid, aqueous formicacid, and the like. These acids will volatilize upon nebulization or canbe diluted in the aqueous solution, thereby decreasing the concentrationof the acid and reversing the solubility of the carrier even in theabsence of a precipitator. For example, see U.S. patent application No.08/475,882, filed on Jun. 7, 1995, now, U.S. Pat. No. 5,667,806,(attorney's docket no. 1946/09202) entitled "SPRAY DRYING METHOD ANDAPPARATUS".

Microsphere formation occurs when the concentration of the acid in thecarrier/active agent solution is decreased. As this solution isnebulized, the acid evaporates, decreasing the concentration of the acidin solution to less than 30% by volume. The carrier, then, will selfassemble to form microspheres containing any optional active agent. Thecargo must be stable in the concentrated acid for the time andconditions necessary to carry out the operation. Alternately, thecarrier solution can be diluted, such as with water, whereby the acidconcentration is decreased and the carrier precipitates to formmicrospheres. Preferably, the microspheres are prepared by spray drying.

The microspheres can be pH adapted by using base or acid solublecoatings including, but not limited to, proteinoid coatings, entericcoatings, acylated amino acid coatings, and the like.

Any of the solutions above may optionally contain additives such asstabilizing additives. The presence of such additives promotes thestability and dispersability of the active agent in solution. Thestabilizing additives may be employed at a concentration ranging betweenabout 0.1 and 5% (w/v), preferably about 0.5% (w/v). Suitable, butnon-limiting examples of stabilizing additives include buffer salts, gumacacia, gelatin, methyl cellulose, polyethylene glycol, and polylysine.

The amount of active agent that may be incorporated in the microsphereis dependent upon a number of factors which include the concentration ofactive agent in the solution as well as the affinity of the active agentfor the carrier. The concentration of the active agent in the finalformulation also will vary depending on the required amounts for anyparticular end use. When necessary, the exact concentration can bedetermined by, for example, reverse phase HPLC analysis.

The microspheres and, therefore, the solutions described above may alsoinclude one or more enzyme inhibitors. Such enzyme inhibitors include,but are not limited to, compounds such as actinonin or epiactinonin andderivatives thereof.

The microspheres are particularly useful for administering itraconazolederivatives to any animals, including but not limited to, birds andmammals, such as primates and particularly humans; and insects. Thesemicrosphere systems are particularly advantageous for delivering theseactive agents as the active agent would otherwise be destroyed orrendered less effective by conditions encountered before the microspherereaches the active agent target zone (i.e., the area in which the activeagent of the delivery composition are to be released) and within thebody of the animal to which they are administered. Furthermore, thesemicrospheres can deliver relatively high amounts of the imidazolederivative and retain a high bioavailability.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following examples illustrate the present invention withoutlimitation.

EXAMPLE 1

Solubilization of Itraconazole

Acetic acid solutions were prepared in water to 10%, 20%, 50% and 75%concentrations (expressed as volume glacial acetic acid/total volume ofsolution ×100). 100 mg itraconazole solute were then mixed independentlywith 1 ml of each solution and visually monitored for dissolution. Ifnecessary, additional 1 ml aliquots of each acetic acid solution wereadded until the itraconazole solute was dissolved.

Results are illustrated in Table 1 below. The solubilized material didnot precipitate readily.

                  TABLE 1                                                         ______________________________________                                        SOLUBILITY                                                                    Concentration                                                                          Amount of Solvent                                                    of Acid  1 ml   1 ml   2 ml 2 ml 3 ml 3 ml 4 ml 4 ml                          in Solvent                                                                             Cold   Hot    Cold Hot  Cold Hot  Cold Hot                           ______________________________________                                        10% Acetic                                                                             Ins.   Ins.   Ins. Ins. Ins. Ins. --   Ins.                          Acid v:v                                                                      20% Acetic                                                                             Ins.   Ins.   Ins. Ins. Ins. Part --   --                            Acid v:v                              Sol.                                    50% Acetic                                                                             Ins.   Ins.   Ins. Sol. Ins. --   --   --                            Acid v:v                                                                      75% Acetic                                                                             Sol.   --     --   --   --   --   --   --                            Acid v:v                                                                      ______________________________________                                    

EXAMPLE 2

Solubilization of Itraconazole

100 mg of itraconazole solute were dissolved in 1 ml glacial acetic acidsolvent and aqueous acetic acid solvent at various concentrations.Results are illustrated in Table 2 below.

                  TABLE 2                                                         ______________________________________                                        ITRACONAZOLE SOLUTE                                                           % Acetic Acid (v:v)                                                                           Dissolved Itraconazole %                                      ______________________________________                                        100             >33 (dissolves freely on addition)                            75              >10 (dissolves freely on addition)                            40               5 (diss.conc.acid, then dilute)                              20               2.5 (diss.conc.acid, then dilute)                            ______________________________________                                    

EXAMPLE 3

Preparation of Itraconazole-containing Microspheres One-solution Method

60 grams of itraconazole solute (Janssen Pharmaceutica) were added to1.43 liters of glacial acetic acid solvent, and the mixture was stirredto dissolve the solute. 1.43 liters of water were then added using apump at a flow rate of 25 ml/min. Slight clouding of the solution wasobserved, but cleared upon further stirring. 166 grams of proteinoid(Glu-Asp-Tyr-Phe-Orn) were added and dissolved with further stirring.The final solution was filtered through folded tissue paper.

Using peristaltic pumps, the solution was fed through a Virtis SDO4spray drying apparatus under the conditions of Table 3 below.

                  TABLE 3                                                         ______________________________________                                        SPRAY DRYING CONDITIONS                                                       Solution flow rate                                                                             7-8 ml/min                                                   ______________________________________                                        Inlet temperature                                                                              175° C.                                               Outlet temperature                                                                             116° C.                                               Blower speed     full                                                         Compressor pressure                                                                            full                                                         ______________________________________                                    

Stable proteinoid microspheres containing itraconazole were formed.Analysis of typical microspheres using RP-HPLC demonstrated that theycontained 14-21% itraconazole by weight.

Scanning electron microscopy in FIGS. 1A-1H illustrates that themicrospheres were smooth and spherical and had diameters ranging from0.1 μm to about 5 μm. When mechanically crushed only the larger spheresshattered, while the smaller spheres remained intact. Crushing revealeda solid internal structure. See, FIGS. 1G and 1H.

All patents, applications, publications, and test methods mentionedherein are hereby incorporated by reference in their entirety.

Many variations of the present invention will suggest themselves tothose skilled in the art in light of the above-detailed description inwhich obvious variations are within the full intended scope of theappended claims.

What is claimed is:
 1. A solution comprising:(a) at least about 2.5parts by weight, based upon 100 parts by weight of solution, of a solutecomprising itraconazole; and (b) a solubilizing effective amount of asolvent comprising at least one volatile organic acid.
 2. A solution isdefined in claim 1, wherein said solution comprises from about 3 toabout 40 percent by weight of solute and from about 60 to about 97 partsby weight of solvent based upon 100 parts by weight of solution.
 3. Asolution as defined in claim 1, wherein said solvent comprises anaqueous solution of said acid.
 4. A solution as defined in claim 3,wherein said solvent comprises aqueous acetic acid.
 5. A solution isdefined as in claim 3, wherein said solvent comprises aqueous formicacid.
 6. A solution as defined in claim 3, wherein said solventcomprises from about 30 to about 80 parts by volume of acid and fromabout 70 to about 20 parts by volume of water, based upon 100 parts byvolume of solvent.
 7. A solution as defined in claim 6, wherein saidsolvent comprises from about 40 to about 50 parts by volume weight ofacid and from about 60 to about 50 parts by volume of water, based upon100 parts by volume of solvent.
 8. A solution is defined in claim 3,wherein the volume:volume ratio of acid to water in said solvent is atleast about 3:7.